Molded discharge lamp



March 22, 1949. H. R. RUFF ET AL 2,465,123

MOLDED DISCHARGE LAMP Filed Aug. 1, 1947' 2 Sheets-Sheet l lnvenTor-s Hourold R. RUFF, Raymond L. Russell.

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Their- ATTorne March 22, 1949. H. R. RUFF ET AL 2,465,123

MOLDED DISCHARGE LAMP Filed Afig. 1, 1947 2 Sheets-Sheet 2 Invervt'ors Hero Id 12. RUFF. Raymond L. EusSl I,

by UN 0. Their Atco e9.

Patent ed Mar. 22, 1949 MOLDED DISCHARGE LAMP Harold R. Rut! and Raymond L. Russell, Rugby,

England. assignors to General Electric Company, a corporation of New York Application August 1, 1947, Serial No. 765,428 In Great Britain August 9, 1946 3 Claims." (01.176-122) This invention relates to electric discharge lamps of the kind in which an elongated discharge column is present during operation. The invention is thus applicable to low pressure electric discharge lamps of the fluorescent type, that is to say, lamps in which the envelope contains two widely separated electrodes, at least one of which is usually thermionic during operation, a fllling of gas and metal vapour at such a pressure that, during operation, a diffuse discharge, mainly confined to the positive column, takes place between the electrodes, and on at least a part of the inner wall of the envelope a coating of luml nescent material which is energized by the d scharge to emit light of a different spectrum from that produced by the discharge. Mercury vapor at an operating pressure of about 1 to microns is commonly used in such lamps. It is also applicable to electron discharge lamps of the kind in which the light is emitted directly by the discharge.

The envelopes of such lamps are generally in the form of a glass tube of a length which depends on the design characteristics of the lamp and is frequently of the order of 4 feet. Such elongated light sources have obviously to be employed with special fittings designed to utilize the light emitted to the best advantage. They have generally, therefore, been used for lighting large areas such as oflices, factories, and public buildings and are generally less suitable for domestic requirements.

It has been suggested to overcomethis inherent disadvantage of fluorescent lamps and render them suitable for the more compact type of fitting generally found on domestic premises by causing the discharge path to occupy a sinuous compact form. The lamp suggested consists of a disc-shaped vitreous envelope formed of coinciding moulded portions, hermetically sealed together to provide a discharge chamber of relatively large area and closely spaced walls. The discharge chamber is provided with one or more partitions which prevent the discharge from taking the shortest path between the electrodes and cause the discharge to take a sinuous form. The partitions are formed by suitably shaping the mould in such a way as to provide on the two halves of the moulded disc projecting portions which coincide when the two moulded portions are placed together.

It is an object of the present invention to provide a different and improved method for providing such a compact design of fluorescent lamp. Another object is to provide an improved lamp of the above type. Other objects and advantages of the invention will appear from the following description.

According to the invention an electric discharge lamp of the kind set forth consists of two grooved vitreous members which are placed faceto-face with an intermediate plate of'vitreous material between them to form two chambers, the grooved vitreous members being sealed together at their periphery, with, if desired, the intermediate plate sealed between them, an aperture or apertures being so locatedin the intermediate plate as to connect the chambers and cause the discharge between the electrodes to take a sinuous path including the aperture or apertures in the plate.

The grooved vitreous members are preferably formed by a mouldin process, and, in general, for convenience of mounting, it is preferable that both the electrodes between which the discharge takes place should be sealed into the wall of the same vitreous member, as this will greatly facilitate the supporting of the discharge device in a suitable mounting socket. In this event, the intermediate plate will necessarily include two apertures through which the discharge passes in succession and the grooving of the vitreous members will be such that the discharge is prevented from taking the shortest path between the two electrodes. The intermediate partitions between the grooves in the vitreous members will be arranged to project to a plane in which the face of the intermediate member will lie when assem-' bled with the vitreous members, so that when the members are placed in contact with the intermediate plate, the grooves and apertures form a continuous path which the discharge is compelled to take. The discharge will then flow from one electrode through a preferably sinuous path occupying substantially one half of the area of one member, through an aperture in the intermediate plate, through a sinuous path occupying substantially the whole of the second vitreous member, and then through the second aperture, back to the second spaced electrode. By suitable design of the grooved vitreous members the discharge path may be made substantially symmetrical on both sides of the intermediate plate.

When both electrodes are mounted in the same vitreous member it will not be possible to make both vitreous members from exactly the same mould, since apertures for the rcception of stems supporting the electrodes will be required in one member and not in the other. The vitreous member which does not support the electrodes will also have to be somewhat modified to allow for a continuous discharge path. The same mould may, however, be employed for producing both members, if removable inserts are adopted for the mould permitting half the mouldings to be made with the removable inserts in position and the remainder without.

In the case in which the electrodes are situated one in each mould, the two mouldings may be made, by suitable design, exactly the same, and

only one aperture will be required in the intermediate plate. Fluorescent material may be applied to the surfaces oi. the mouldings and the plate defining the discharge path and a reflecting metal coating may be applied to the outer surface oi! one of the mouldings to increase the light in one direction.

For the purpose of enabling the invention to be more readily understood, reference is directed to the accompanying drawings, in which Fig. 1 in a plan view shows a grooved vitreous member, two of which are required with an intermediate plate to form a discharge lamp; Fig. 2 illustrates in a similar view the assembled lamp showing the manner in which the two mouldings are superposed on the glass plate to obtain the required effect; Figs. 3 and 4 are cross-sections, respectively, of Figs. 1 and 2; Fig. 5 is a plan view of a grooved vitreous member having two electrodes sealed into its wall; Fig. 6 is a sectional view thereof taken along the line 6-6 of Fig. 5 and in the direction of the arrows; Fig. 7 is a plan view of a grooved vitreous member having no electrodes sealed into its walls; Fig. 8 is a sectional view thereof taken along the line 8-8 of Fig. '1 and in the direction of the arrows; Fig. 9 is a plan view of the lamp comprising the two members shown in Figs. 5 to 8; andFig. 10 is a sectional view thereof taken along the line l--I0 of Fig. 9 and in the direction of the arrows.

Referring to Figs. 1 and 3 the moulding is in the form of a grooved glass disc having an outer rim I, and an intermediate partition 2 produced by using a mould or corrugated form. As shown in Figs. 2 and 4 the two mouldings are assembled together with the intermediate plate 3 between them, in such a manner that the two mouldings are angularly spaced so that the substantially radial portions 4 of the partitions 2 are arranged to form two legs of a substantially equilateral triangle. An aperture is located in the intermediate plate in the centre of the triangle. The discharge between the electrodes 6 thus takes place along the interrupted line indicated on Fig. 1, which shows the lower moulding, the discharge .passing upwardly through the aperture 5 (Fig. 2)

and then through the upper moulding back to the electrode 6 situated on the upper moulding.

Since the form of lamp envelope shown in Figs. 1 to 1 of the drawings is one in which the electrodes are located, one in each disc, light will be emitted uniformly in directions transverse to the plane containing the intermediate plate, the coating of luminescent material being provided on the concave surfaces of the grooves in the disc and on the opposed surface of the intermediate plate. Light emission of the'lamp may be increased in one direction by forming a mirror surface on the outer surface of one grooved member. A similar surface, such as one of sputtered aluminum, to reflect ultraviolet light may be applied to the intermediate plate.

The lamp shown in Figs. 5 to of the drawings comprises a grooved glass disc I having two electrodes 8 and 9 (Figs. 5 and sealed therein on opposite sides of the partition ill which is circular in part and has two reversely curved partions II and I2 joining the rim [3 of the glass disc I. The other glass disc 14 (Figs. '7 and 8) is similar to the disc I but has no electrodes sealed therein and the partition 15 thereof has but one reversely curved portion l5 joining the rim I! of the disc H. The other reversely curved portion is omitted from the partition ll so that the discharge' path may extend around the outside of the partition I! and into its center as indicated by the broken lines and the arrows of Fig. 7. 'Ihe,

two discs I and I4 are superimposed on and fused to the intermediate glass plate I! (Figs. 9 and 10) which has an aperture 19 in its center and another aperture 20 near its edge.

As indicated by the arrows in Figs. 5 and 7 the discharge path extends from the electrode I around the outside oi! the partition I0 0! the disc 1, up through the aperture 20 of plate I! into disc I4, around the outside of partition I5 of disc ll to the center aperture 19 in the plate I! and thence through the aperture l9 into disc 'I and to electrode 8.

What we claim as new and desire to secure by Letters Patent 01 the United States is:

1. A gaseous conduction lamp comprising a disc-shaped envelope made up of a circular vitreous plate having an aperture therein and concave dish-shaped vitreous members disposed face-to-face with the plate between them, said members having circular grooves therein 01 the same radius extending an angular distance oi. less than 360 and communicating with said aperture to define with said plate a discharge path having concentric circular sections of equal radius on opposite sides of said plate.

2. A gaseous conduction lamp comprising a disc-shaped envelope made up of a circular vitreous plate having an aperture adjacent its periphery and concave dish-shaped vitreous members disposed face-to-face with the plate between them, said members having concave center portions and circular grooves around and communicating with said portions, said grooves being of equal radius, extending an angular distance of less than 360 and communicating also with said aperture to define with said plate a discharge path having concentric circular sections of equal radius on opposite sides of said plate.

3. A gaseous conduction lamp comprising a disc-shaped envelope made up of a circular vitreous plate having an aperture adjacent its periphery and another aperture at its center and concave dish-shaped vitreous members disposed face-to-face with the plate between them, said members having concave center portions communicating with the center aperture in said plate 4 and circular grooves around and communicating with said center portions, said grooves being of equal radius, extending an angular distance of less than 360 and communicating also with the aperture adjacent the rim of the plate to define with said plate a discharge path having concentric circular sections of equal radius on opposite sides of said plate.

HAROLD R. RUFF. RAYMOND L. RUSSELL.

REFERENCES CITED The following references are of record in the file of this patent: 

